I have the same issue. Dates displayed correctly (meaning, conforming to my PC settings of DD-MM-YYYY) when I was using MM 3, but now that I've switched to the 64-bits version of MM 4, dates show as mm/dd/yyyy whenever I start up MM.
I can add one more strange aspect to this annoying problem... When I enter dates, and use the format I expect my PC to use (DD-MM-YYYY), MM interprets them as mm/dd/yyyy anyway. Now that's not so strange, considering the problem this thread is about. But what's even weirder is that when the first part of the date is higher than 12 (which makes total sense if the format is DD-MM-YYYY), MM automatically switches around the first and second parts of the date entered! This means you have now entered the wrong date, but will probably not even notice it.
How hard can it be to fix this? It's just a matter of correctly using the date format on the PC (and applying that to data entry and to the date stored in the tag).